1. Field of the Invention
The present invention relates to novel amphiphilic polyether polyurethanes which can be converted into, low encrustation, swellable, soft, biocompatible, hydrated unitary materials having specific hardness and swellable properties and superior wet tear and tensile strengths for use in intravenous, central venous, dialysis, and cardiovascular catheters, vessels, ports, synthetic veins and arteries, gaskets, medical stents, drug delivery systems, medical, cosmetic, shaving and industrial applications. The present invention also relates to novel polyether polyurethanes which can be converted into polymers which form spreadable, foams, solutions, dispersions and gels for use as creams, lotions, antiperspirants, emulsifiers, hair conditioners, drug and fragrance delivery systems, and coatings of rubber products, and which form breathable, nongreasy, water-resistant, tough, biocompatible, soft, and lubricious films.
2. Description of the Related Art
Hydrophobic and hydrophillic polymers are known and have been used for forming articles such as catheters and body implants with improved swelling properties. U.S. Pat. No. 4,883,699 describes a body implant comprising a multiple phase polymer having one phase with a substantially non-hydrophilic polymer and another phase having a hydrophilic polymer. This swollen and softened material has high strength. The polyurethane is hydrophobic and the hydrophilic material is polyethylene oxide, which is susceptible to leaching, eluting from water. Further, the hydrophobic and hydrophilic materials are blended together, to form a composite. The swelling rate depends upon the water reaching the hydrophilic material and its rate is slowed by the surrounding hydrophobic polymer.
U.S. Pat. No. 4,994,047 ('047 patent) describes a swellable cannula formed of concentric inner and outer hydrophilic and substantially non-hydrophilic layers. The hydrophilic layer is at least 2/3 of the cross-sectional layer of the wall of the cannula. Polyoxyethylene oxide is used as the hydrophilic material. This patent suggests that swelling and softening polymers described in U.S. Pat. Nos. 4,359,558, 4,424,305, 4,454,309, and 4,439,583 may be incorporated into the cannula as hydrophilic materials. The polyurethane-diacrylate polymers are not readily extrudable because the diacrylate monomers form cross-linked networks, possibly even cross-linking the polyurethanes. The '047 patent has the shortcoming that the rate of softening of the inner hydrophilic layer is low, and the use of an outer hydrophilic layer can quickly swell the outside of the cannula, but the diameter of the cannula does not increase until its unstable layer is hydrated.
U.S. Pat. Nos. 3,822,238 and 3,975,350 describe a class of hydrophilic polyether polyurethanes containing about 0.3% of water. The hydrophilic polyurethanes absorb water and are cross-linked. The softness-hardness ratio of the polymers was modified by varying the ratio of soft (--OC.sub.2 H.sub.4 --) units to hard alkylene units of (--C.sub.2 H.sub.4 OC.sub.2 H.sub.4 --). The increase in hard units of the polymers increases rigidity of the polymer. An increase in soft units of the polymers results in the polymers being weak, especially in the wet and swollen state. The cross-linked polymer does not lend itself to extrusion into tubing with precise dimensions.
U.S. Pat. No. 4,789,720 of common ownership with the present disclosure overcame some of the above described shortcomings. A hydrophilic polyurethane is formed comprising polyoxyethylene glycol and polyoxypropylene glycol (PPG) and water in the reaction mixture of less than about 0.5% weight percent. The polyurethanes are particularly useful for body implants and feeding tubes. This patent teaches the use of PPG imparts higher dry and wet tensiles to the polymers without substantially diminishing their hydrophilic properties. The use of large amounts of PPG has the drawback of causing considerable blocking of the polymers and reducing the hydrophilicity of the polymer. This reduction in hydrophilicity is disadvantageous in certain applications such as medical device products in which it is advantageous to have high water contents and expansions.
U.S. Pat. No. 5,120,816, of common ownership with the present disclosure, describes a polyurethane resin having improved tear strength in which the amount of water in the reaction mixture is in the range of about 1.0% to about 2.5% weight percent. The reaction product includes a diol formed of a long chain polyoxyethylene glycol and a medium chain polyoxyethylene glycol. The polymers have the shortcoming of not being readily extrudable.
U.S. Pat. No. 5,102,401 ('401 patent) teaches the use of a hydrophobic polymer coextruded over a hydrophilic polymer made with aromatic and aliphatic diisocyanates, in order to reduce the rate of swelling. The swelling rates for the uncoated catheters are 10% in one minute and 21% after 10 minutes. The swelling rate for the hydrophobic coated catheter reached 3.6% in four minutes and 14.7% in 10 minutes. These values were superior to those for a noncoated hydrophilic expandable catheter such as 20 gauge Streamline.RTM., Menlo Care, Inc., Palo Alto, Calif. catheter, described in the preceding patents, which reached 9% swelling in 60 minutes. Typically, nurses and doctors insert and remove needles within two to three minutes, and want the catheter to swell quickly to a high value. Accordingly, the catheters described in the '401 patent have the shortcoming of not swelling fast enough to meet the needs of health-care professionals.
U.S. Pat. No. 5,000,955 describes a thermally reversible gel comprising a polyether polyurethane formed using a mixture of anhydrous polyoxyethylene diols, alkylene glycol and an aliphatic diisocyanate. The viscosities of the gel drops as the temperature was increased from room temperature to body temperature. U.S. Pat. No. 5,273,742 describes solutions of polyether polyurethanes for use in eye surgery and arthritic operations.